Application of the Hilbert-Huang transform for analyzing standing-accretion-shock-instability induced gravitational waves in a core-collapse supernova

TL;DR

This paper demonstrates the use of the Hilbert-Huang Transform to analyze gravitational waves from a supernova simulation, successfully extracting signals associated with the standing-accretion-shock-instability with high time-frequency resolution.

Contribution

It introduces the application of the Hilbert-Huang Transform to gravitational wave analysis from supernovae, providing high-resolution insights into specific GW modes linked to explosion mechanisms.

Findings

Successfully extracted SASI-induced GWs with high resolution

Analyzed instantaneous frequencies of GW modes

Enhanced understanding of supernova explosion mechanisms

Abstract

Through numerical simulations, it is predicted that the gravitational waves (GWs) reflect the characteristics of the core-collapse supernova (CCSN) explosion mechanism. There are multiple GW excitation processes that occur inside a star before its explosion, and it is suggested that the GWs originating from the CCSN have a mode for each excitation process in terms of time-frequency representation. Therefore, we propose an application of the Hilbert-Huang Transform (HHT), which is a high-resolution time-frequency analysis method, to analyze these GW modes for theoretically probing and increasing our understanding of the explosion mechanism. The HHT defines frequency as a function of time, and is not bound by the trade-off between time and frequency resolutions. In this study, we analyze a gravitational waveform obtained from a three-dimensional general-relativistic CCSN model that showed a vigorous activity of the standing-accretion-shock-instability (SASI). We succeed in extracting the SASI induced GWs with high resolution on a time-frequency representation using the HHT and we examine their instantaneous frequencies.